1. Technical Field
The present invention relates to a portable computer system and a method for controlling the portable computer system.
2. Related Art
Portable computers are well known, in which a computer body, a monitor, and a keyboard are integrally coupled together to provide a portable structure, as compared to so called “desktop computers”, in which a computer body, a monitor, and a keyboard are configured to be separated from one another, so that they are used in a state laid on a desk, for example. Such a portable computer includes a computer body having a main board mounted with a central processing unit (CPU), a random access memory (RAM), a disk driver, a graphic card, and other diverse cards, a monitor electrically connected to the computer body and adapted to externally transmit a video signal from the computer body, and an input unit including a keyboard and a mouse to input desired information to the computer body. A portable computer can be a laptop computer, a notebook computer, a personal digital assistant (PDA), a palm-sized computer, or other type of movable computer.
Typically, portable computers mentioned above perform a power management function. A power management system has been developed from that having a simple power management function, which was developed at the early development stage, relative to that having an advanced power management function. Current IBM-compatible computer systems mainly use the power management system having the advanced power management function of an advanced power management (APM) system in order to achieve a considerable reduction of the power consumption.
Meanwhile, a computer system is processed in accordance with a booting procedure proceeding from a booting by a basic input output system (BIOS) to a booting by an operating system so that it is booted to allow the user to use the computer system after a power-on of the computer system. In association with the booting procedure, however, the computer system inevitably involves an increase in booting time resulting from an increased complexity of its configuration and increased numbers of operating systems and diverse application programs loaded therein.
In order to achieve an improved power management and a rapid re-use of the computer system, Intel Corporation, Microsoft Corporation, and Toshiba Corporation have issued “Advanced Configuration and Power Interface (ACPI) Specification Revision 1.0” on Dec. 22, 1996. Computer systems recently developed are configured to meet the ACPI specification so that they achieve an improved power management and a rapid booting procedure.
In accordance with the ACPI specification, the power management state of a computer system is mainly defined by 6 sleeping states, that is, S0 to S5-states. The S0-state corresponds to a normal state. The S1 to S4-states correspond to states in which the power consumption is gradually reduced, respectively, whereas the S5-state corresponds to a state in which the supply of power to the entire portion of the computer system is cut off. The computer system having the above mentioned power management function uses a power supply device having a power supply configuration providing a main power and a standby power, separated from each other, to support an ATX specification. The power supply device supporting the ATX specification always outputs the standby power in a state in which an external power is applied. The standby power is supplied to a power management controller included in the computer system.
The S3-state according to the ACPI specification is adapted for a rapid re-use of the computer system. In the S3-state, the supply of power to all hardware units of the computer system, except for the system memory (RAM) formed by volatile memories and the power management controller, is cut off. The procedure, in which the computer system enters the S3-state, is referred to as a “suspend-to-RAM”. During this suspend-to-RAM procedure, a system context is stored in the system memory.
When a mode corresponding to the S3-state is set in the computer system, the content of the current task is stored in the system memory, that is, RAM. Following this storage, the supply of power is completely cut off. The task content stored in the system memory is retrieved in a wake-up operation for converting the operating mode of the computer system from the S3-state to a normal state, so that the computer system can be rapidly re-used without any execution of the general booting procedure. Thus, it is natural that the user is favorable to computer systems capable of supporting the S3-state according to the ACPI specification, thereby achieving an effect of greatly reducing the power consumption while allowing a rapid system re-use.
In the S3-state, it is possible to minimize the power consumption because the computer system enters the standby mode under the condition in which the content of the current task has been stored in the RAM formed by volatile memories. Also, there is an improvement in processing efficiency in that when power is applied again to the computer system for a re-execution of the task, the task content stored in the RAM is retrieved in response to the re-application of power to the computer system.
Meanwhile, the power consumption made by diverse devices mounted to the computer system, such as a central processing unit (CPU), a compact disc-read only memory (CD-ROM), a hard disk drive (HDD), and a modem, is carried out in a stepwise fashion in accordance with the state of the computer system. That is, the power consumption state of the computer system is defined by C0 to C3-states associated with the central processing unit, and D0 to D3-states associated with the compact disc-read only memory (CD-ROM), a hard disk drive (HDD), and modem.
Here, a lower number of the power consumption state corresponds to a reduced power consumption. Accordingly, the C0-state corresponds to the state in which the central processing unit is fully driven. In this state, the central processing unit is allowed to recognize peripheral devices. In the C2-state, the central processing unit is still driven. In this C2-state, however, outputting of information from a phase locked loop (PLL) included in the central processing unit is cut off. In a manner similar to the C0-state, the central processing unit is still allowed to recognize the peripheral devices in the C2-state.
Where the peripheral devices are not driven, it is desirable to fundamentally cut off the transmission of signals from those peripheral devices to the central processing unit, thereby preventing the central processing unit from recognizing the peripheral devices. In accordance with this configuration, it is possible to avoid an unnecessary power consumption. This state corresponds to the C3-state. In this C3-state, a further reduction in power consumption is achieved. This provides an advantage in that the portable computer can be used for an increased period of time in every discharge operation.
In a portable computer system, however, there may be a disadvantage where a separate Universal Serial Bus (USB) hub is mounted to the computer system in order to mount diverse devices such as MP3 and Bluetooth devices. That is, the central processing unit of the computer system repeatedly conducts an unnecessary checking procedure for the Universal Serial Bus hub and associated devices, even when those devices are in an inactive state. The repeated checking operation can be considered a polling operation. The polling operation can be performed to see if a device is present, to check the status of a device, to identify a device, to see if a device has been removed, and for other reasons. Bluetooth is a wireless short-range networking technology intended to simplify communications among devices such as portable computers, mobile telephones, digital cameras, printers, and other devices.
Due to the repeated checking operation of the central processing unit for the Universal Serial Bus hub and associated devices, the computer system cannot be maintained in the C3-state, thereby resulting in an increase in power consumption. Furthermore, the generation of heat in the computer body increases. This results in a problem in that the memory and diverse chips internally installed in the computer body may be damaged, so that their life is reduced.